Susan G Komen  
I've Been Diagnosed With Breast Cancer Someone I Know Was Diagnosed Share Your Story Join Us And Stay Informed Donate To End Breast Cancer
Home > Understanding Breast Cancer > Breast Facts > What is Breast Cancer? > What is Lobular Carcinoma in Situ (LCIS)?


What is Lobular Carcinoma in Situ (LCIS)?


When abnormal cells grow inside the lobules of the breast, but have not spread to nearby tissue or beyond, the condition is called lobular carcinoma in situ (LCIS). The term "in situ" means "in place." With LCIS, the abnormal cells are still "in place" inside the lobules. Although the term LCIS includes the word “carcinoma,” LCIS is not invasive breast cancer.     

Most cases of LCIS occur before menopause [8].   


Image source: National Cancer Institute (

Lobular carcinoma in situ (LCIS) and breast cancer risk

Although LCIS is not invasive cancer, it increases the risk of getting invasive breast cancer in either breast.

LCIS has been considered a risk factor for breast cancer, but not a precursor (a condition that can develop into) to breast cancer. However, recent evidence shows some LCIS may develop into invasive lobular carcinoma (invasive breast cancer that begins in the lobules) [8-10].

Learn about LCIS and the risk of invasive breast cancer.

Breast cancer screening for women with LCIS

Because LCIS increases the risk of breast cancer, the National Comprehensive Cancer Network (NCCN) has special screening recommendations for women with LCIS. Women with LCIS should [11-12]: 

This medical care helps ensure that if breast cancer does develop, it is caught early when the chances of survival are highest.

Risk-lowering options for women with LCIS

Risk-lowering drugs (chemoprevention)

Tamoxifen and raloxifene    

Women with LCIS may take tamoxifen or raloxifene to try to lower the risk of invasive breast cancer [13]. Tamoxifen and raloxifene only reduce the risk of estrogen receptor-positive breast cancers. Neither drug reduces the risk of estrogen receptor-negative cancers [14].

Tamoxifen lowers the risk of breast cancer by about 50 percent and raloxifene lowers risk by about 38 percent [14]. Although raloxifene is slightly less effective than tamoxifen in reducing breast cancer risk, it has fewer harmful health effects [14]. This makes raloxifene a better choice for some women.

Raloxifene is only for use among postmenopausal women, while both pre- and postmenopausal women can use tamoxifen.

Learn more about tamoxifen and raloxifene.


For a summary of research studies on the use of tamoxifen and raloxifene to reduce breast cancer risk, visit the Breast Cancer Research section.

Aromatase inhibitors  

Aromatase inhibitors are part of standard hormone therapy for estrogen receptor-positive breast cancer in postmenopausal women (learn more). These drugs are now being studied to see whether they lower the risk of breast cancer in postmenopausal women at higher risk, including women with LCIS.

Findings from a randomized controlled trial showed the aromatase inhibitor exemestane (Aromasin) lowered the risk of breast cancer in postmenopausal women at higher risk (learn more) [15]. Although exemestane is FDA-approved for use in breast cancer treatment, it does not yet have FDA-approval for use as a risk-lowering drug.

Learn about emerging areas in risk-lowering drugs for women at higher risk of breast cancer.

Learn about exemestane and other aromatase inhibitors and breast cancer treatment.

Preventive surgery (prophylactic mastectomy)

A drastic option for lowering breast cancer risk is to have a prophylactic bilateral mastectomy. This surgery involves removing both breasts to try to keep cancer from developing.

Because tamoxifen and raloxifene are effective in greatly reducing risk, most women with LCIS choose this option (along with recommended breast cancer screening) over prophylactic bilateral mastectomy. Talk to your health care provider about the risks and benefits of these options so you choose the one that is best for you.

Learn more about options for women at higher risk.  

Komen Support Resources  

  • Our breast care helpline 1-877 GO KOMEN (1-877-465-6636) provides free, professional support services and help finding local support groups. Our trained and caring staff are available to you and your family Monday through Friday from 9:00 a.m. to 10:00 p.m. EST and from 6:00 a.m. to 7:00 p.m. PST. 
  • Our Message Boards offer online forums to share your thoughts or feelings about subjects related to breast cancer. Our Women at Higher Risk of Breast Cancer forum within the Message Boards offers women at higher risk a place to share their own unique experiences and challenges.


Updated 03/16/14


What is Breast Cancer? 

Benign Breast Conditions
(Benign Breast Disease)